WO2009000632A2

WO2009000632A2 - Electric motor and method for producing an electric motor

Info

Publication number: WO2009000632A2
Application number: PCT/EP2008/057146
Authority: WO
Inventors: Marcel Fankhauser; Gerhard Oberli; Roland Schrag
Original assignee: Robert Bosch Gmbh
Priority date: 2007-06-27
Filing date: 2008-06-09
Publication date: 2008-12-31
Also published as: EP2162972A2; WO2009000632A3; DE102007029743A1

Abstract

The invention relates to an electric motor comprising a housing (82) and a first bearing flange and a second bearing flange (10, 40). According to the invention, an edge (88, 90) of the housing is radially inwardly flanged over at least one of the bearing flanges (10, 40) along the periphery thereof.

Description

description

title

Electric motor and method for producing an electric motor

State of the art

The invention relates to an electric motor and a method for producing an electric motor according to the preambles of the independent claims.

It is known to encapsulate electric motors to prevent the ingress of foreign bodies or moisture. Various techniques are used for this. So can be achieved by screwing, caulking or by deep drawing tight closure of the electric motor. The common techniques are relatively expensive in production.

When using the electric motor in power tools such as rotary hammers, must be reckoned with large axial loads resulting from vibrations in the hammer mechanism. Measurements have shown that axial forces of up to 3000 N can act on a rotor that experiences very high accelerations up to 100 g in a hammer drill. Furthermore, tightness must be ensured in relation to normal grease lubrication of the bearings and protection against the ingress of dust, chips or other foreign bodies. So can metal shavings by the magnetic

Adhere to attraction on the rotor and thus cause damage to the copper winding by the rotation, resulting in the failure of the electric motor. Dust and concrete components can accumulate in the bearing, slowing the engine, causing overheating and failure. These boundary conditions must be taken into account in the encapsulation of the electric motor.

With open electric motors, the penetration of foreign bodies can only be avoided with great effort and compromise. Thus, cross struts are attached to the housing shells, which are intended to prevent the penetration of coarser foreign bodies. However, this has the consequence that the cooling of the electric motor deteriorates and the

Electric motor is exposed to an elevated operating temperature. Dust and concrete particles however, they can hardly be effectively prevented. The tooling costs of the injection molds for the housing shells are very expensive, as well as changes in the tools. With high costs and increased deadline, it may be necessary to make subsequent corrections.

Disclosure of the invention

The invention relates to an electric motor with a housing and a first and a second bearing flange.

It is proposed that a housing edge is crimped circumferentially radially inwards over at least one of the bearing flanges. Advantageously, a tight connection between the housing and the bearing flange is achieved. The electric motor is protected against ingress of foreign bodies and dust. The manufacturing costs are advantageously low, and there is a high process capability, so that the electric motor can be advantageously produced in larger series. Advantageously, the connection between the housing and bearing flange is uncritical to temperature changes and can be used over wide temperature ranges. An axial load of the bearing flange during operation of the electric motor is low because the connection is made via a positive connection. The life and reliability of the electric motor is increased.

Preferably, the housing edge can fit positively against the at least one bearing flange. Thus, a high tightness can be improved. It can be achieved a high axial strength over the entire operating temperature range of the electric motor.

If the at least one bearing flange has a shoulder arranged concentrically with respect to a rotation axis, against which the edge of the housing abuts in radial circumferential direction, the mechanical stability and dimensional stability of the connection between housing and bearing flange can be further improved.

Conveniently, the at least one bearing flange having a bearing in a bearing seat, wherein the bearing is overlapped by a flanged contour on its flanschabgewandten side edge. The contour is preferably formed by tangential rivets until it rests positively on the edge of the bearing. Advantageously, the bearing is held so that mechanical stresses or tilting can be avoided. The bearing wear can be reduced.

The invention is further based on a method for producing an electric motor, in which a housing is connected to at least one bearing flange.

It is proposed that a stamp on a bowling alley rotates about an inserted into the housing bearing flange and the housing at its housing edge circumferentially applies to the bearing flange. The process can be easily integrated into a series production and causes only low production costs. High process reliability and process stability can be achieved. Advantageously, the process is controllable by an online process monitoring and thus particularly inexpensive and reliable.

Preferably, the punch with feed and contact pressure can drive continuously on the edge of the housing. The trajectories of the stamp can be adjusted reproducibly, for example with a conventional process control.

The housing edge can conveniently be crimped over the bearing flange until a positive connection between the edge of the housing and the bearing flange is formed. An exact end point of the forming is easily adjustable.

Voreilhafterweise a bearing can be used in the bearing flange and rolled from a Lagerflanschabgewandten side of the bearing ago a punch on a bowling alley over a contour and a part of the contour are radially inwardly folded so that the bearing flange is overlapped by the contour. Advantageously, the bearing is exposed during connection to the bearing flange only low loads. Contrary to a widespread assumption, the realization of a particular fixed bearing side is very demanding. In industrially manufactured engines, it can easily lead to a misalignment of the sensitive ball bearings. This in turn can lead to a poorer efficiency of the electric motor to excessive bearing wear.

The invention is further based on a bearing flange of an electric motor, wherein the bearing flange has an axis of rotation.

It is proposed that an outer circumferential contour which tapers in the axial direction starting from an edge of greater circumference, wherein the contour of the positive connection is provided with a housing edge. Advantageously, a low-cost and highly stable connection with a motor housing can be made with the bearing flange.

The connection is improved if the contour can be rounded in the axial direction.

If a paragraph can be arranged concentrically to the axis of rotation, which is provided as a stop for the housing edge, a particularly good controllable positive connection between the motor housing and the bearing flange can be produced.

Advantageously, the bearing flange having a bearing seat with a bearing body, wherein the bearing body is overlapped on its lagerflanschabgewandten side of the material of the bearing seat. For a particularly gentle attachment of the bearing in the bearing flange is possible.

It is proposed a power tool, in particular a power tool with a striking and / or rotationally driven insert tool, with an electric motor and at least one bearing flange, each having at least one of the features described above. Due to the design-related temperature resistance of the bearing flange housing connection and / or the bearing-Lagerflanschverbindung, the high-quality electric motor has properties that are superior to other electric motors. The preferred power tool is correspondingly robust and reliable.

Brief description of the drawings

drawing

Further advantages emerge from the following description of the drawing. In the drawing, an embodiment of the invention is shown. The drawing, the description and the claims contain numerous features in combination. The person skilled in the art will expediently also consider the features individually and combine them into meaningful further combinations. Show it: 1 shows a longitudinal section through a preferred bearing flange for a movable bearing.

2 shows a longitudinal section through a preferred bearing flange for a fixed bearing.

3a shows a longitudinal section through a preferred bearing flange for a fixed bearing after the inclusion of the bearing in the bearing flange. 3b shows a longitudinal section through a preferred bearing flange for a fixed bearing before inserting the bearing in the bearing flange.

Figures 4a, 4b different views of a preferred housing for an electric motor. 5a shows a longitudinal section through a preferred electric motor prior to the connection of bearing flanges with a housing of the electric motor. Fig. 5b is a longitudinal section through a preferred electric motor according to the

Connection of bearing flanges with a housing of the electric motor; and FIG. 6 shows a preferred power tool.

Embodiments of the invention

In the figures, the same or equivalent elements are numbered by the same reference numerals.

To illustrate the invention, FIGS. 1 and 2 show longitudinal sections of two

Bearing flanges 10 and 40, wherein the first bearing flange 10 is formed for a fixed bearing and the second bearing flange 40 for a floating bearing.

The bearing flange 10 has a first side 12, which faces the electric motor in the assembled state and a second side 14, which faces outward in the mounted state. In a bearing seat 16, a bearing 30 is used with a rotation axis 64, which faces with its outer side 32 a rotor of the electric motor. Starting from an edge 18 with a larger diameter, here the largest diameter of the bearing flange 10, the bearing flange 10 has a rounded contour 24, which tapers towards the second side 14 and ends in a shoulder 26. This serves as a stop in the preparation of the connection between a motor housing and the bearing flange 10th

On the rotor-facing side 12 of the bearing flange 10, a ring 20 is formed radially outside of the bearing 30, which forms an outer edge of the bearing seat 16 and projects beyond the side 32. An edge 22 of the ring 20 designed as a rivet contour is reshaped so that it is folded over radially inwards and the bearing overlaps at the edge. FIG. 2 shows a further embodiment of a bearing flange 40, which is suitable, for example, for a movable bearing, which in principle has a similar construction. The bearing flange 40 has a - in the assembled state - a side facing the rotor 42 and an opposite, outwardly facing side 44. In a bore 46, a bearing can be received, which has a rotation axis 64.

Starting from an edge 48 with a larger diameter, here the largest diameter of the bearing flange 40, the bearing flange 40 has a rounded contour 50, which tapers towards the second side 44 and merges into a planar surface piece.

FIGS. 3a and 3b disclose a further preferred embodiment of the bearing flange 10 of FIG. 1, as it can be used for a fixed bearing. To avoid unnecessary repetition, reference is made to the description of FIG. 1 for the same elements. The bearing flange 10 additionally has a connection piece 28, which protrudes outward on the rotor-remote side 14. The nozzle 28 can serve for rotor bearings. In Fig. 3a, the bearing 30 is inserted into the bearing seat 16 and is overlapped by the edge 22 of the ring 20. Fig. 3b shows the bearing flange 10 in the initial state without bearing 30. The formed as Nietkontur edge 22 of the ring 20 has at the radially outer end of a chamfer, which facilitates the folding of the edge 22 during forming. Visible is a notch 24a, which is incorporated in the edge-side contour 24. One or more such notches 24a, for example, two diametrically opposed notches 24a, serve for torque transmission between the bearing flange 10 and a motor housing. In an engine variant, as e.g. is shown in Fig. 5a, 5b, a gear via end screws, which are screwed into unspecified holes in the bearing flange 10, flanged to the bearing flange 10. The notches 24a serve to increase a holding force between the bearing flange 10 and the housing by means of a preferred tangential riveting, as described in FIGS. 5a, 5b. A holding force that is frictionally engaged without notches 24a may be too small to safely transmit the engine torque. When attaching the two notches 24a, the material in the hundredth to tenths of a millimeter range is "pressed" into the notches 24a, resulting in an advantageous positive power transmission.

After a typically manual insertion of the bearing 30 in the bearing seat 16 of the bearing flange 10, the forming process of the edge 22, which is preferably a tangential rivets follows. When tangential riveting a flat rivet on the rotates rotor-facing side 12 of the bearing flange 10 on a bowling alley, whose apex is located on the axis of rotation 64 of the bearing 30. By means of a controlled feed the riveting punch is continuously on the bearing flange 10 and thus on the Nietkontur (edge 22). The edge 22 is thereby "pushed in" continuously into the bearing seat 16. The deformation is continued until the previously projecting edge 22 no longer protrudes substantially from the end face of the bearing flange 10. In this case, an exact end point of the deformation can be set.

A preferred housing 92 of an electric motor is shown in Figs. 4a and 4b in different views. The housing 82 has a cylindrical

Section 92 on with an upper edge 88 and a lower edge 90. Radially inside a shoulder 84 is formed at the upper edge 88 and at the lower edge 90 a shoulder 86 on which the bearing flanges are to rest later. A cutout 94 in the cylindrical portion 92 serves to lead out electrical connections of a winding body, via which it can be energized in operation. In the longitudinal direction, a groove 96 is provided in the cylindrical portion 92, which can facilitate the forming process.

Figures 5a and 5b show a preferred electric motor 100 in the assembled state (Figure 5a) and after closing the housing 82 (Figure 5b).

In the housing 82, a bearing flange 10 is used with a trained as a fixed bearing 30 at the upper edge 88 and at the lower edge 90, a bearing flange 40 with a designed as a floating bearing 52. For the description of the housing 82, reference is made to Figs. 4a, 4b and for describing the bearing flanges 10 and 40 to the description of Figs. 1, 2, 3a and 3b to avoid unnecessary repetition.

The bearings 30, 52 support a rotor shaft 62 of a rotor 60. On the front side, a fan 80, which can be driven by the rotor shaft 62, is arranged on the outer side of the bearing flange 40.

On the rotor shaft 62, a permanent magnet 66 is attached. The rotor 60 is surrounded by a stator 70, which comprises a stator iron package 72 and a winding body 74 which is radially enclosed by the stator iron package 72. The winding body 74 is arranged in an air gap between the rotor 60 and stator iron package 72. The electric motor 100 is preferably an electronically commutating motor with air gap winding. In Fig. 5a it can be seen that the edges 88, 90 of the housing 82 protrude from the rounded contours 24, 50 of the bearing flanges 10, 40.

5b shows the electric motor 100 with closed housing 82. The upper end 88 is close to the Kontor 24 of the bearing flange 10, the lower end 90 of the housing 82 is close to the contour 50 of the bearing flange 40 at.

The preferred method is a Tangentialnietverfahren and takes place so that after - usually manually - inserting the bearing flanges 10, 40 a riveting on the respective edge 88, 90 of the housing 82 rotates on a bowling alley, the apex is located on the axis of rotation 64. By means of controlled feed and defined pressure, the riveting punch continuously drives the housing 82 and thus the contour 24, 50, which form the rivet contours. The edges 88, 90 are successively crimped over the respective bearing flange 10, 40 or its contour 24, 50, until a desired, clean fit has been set. If one or more notches 24a are provided (FIG. 3b), the material is "pushed" into the notches 24a in the hundredth to tenths of a millimeter range, which is favorable for an advantageous form-locking force transmission between the housing 82 and the bearing flange 10, FIG. on which a gearbox is flanged.

In this case, first the bearing flange 10 can be used with mounted bearing 30, the upper edge of the housing 88 are connected to the bearing flange 10 as described by tangential rivets. Then stator 70 and rotor 60 can be mounted with the further bearing flange 40 with the bearing 50, whereupon the lower housing edge 90 is positively connected to the bearing flange 40 by tangential rivets. The fan can be mounted before connecting housing 82 and bearing flange 40. It is also conceivable to assemble all the parts and then first to connect one of the two bearing flanges 10 or 40 and then the other to the housing 82. Optionally, both housing edges 88, 90 can be connected simultaneously with the bearing flanges 10, 40, with appropriate tool.

Finally, FIG. 6 shows a preferred power tool 110 for battery or mains operation in the form of a power tool 110 with a striking and / or rotationally drivable insert tool 12. The power tool 110 has a preferred electric motor 100 with air gap winding, as described above in FIGS and 5b. The power tool 110 may in particular a be highly stressable power tool 1 10, about an industrial screwdriver, a cordless screwdriver or a hammer drill.

Claims

claims

An electric motor having a housing (10) and a first and a second bearing flange (10, 40), characterized in that a housing edge (88, 90) is crimped peripherally circumferentially radially inwardly over at least one of the bearing flanges (10, 40).

2. Electric motor according to claim 1, characterized in that the housing edge (88, 90) positively against the at least one bearing flange (10, 40).

3. Electric motor according to claim 1 or 2, characterized in that the at least one bearing flange (10) has a concentric with a rotation axis (64) arranged paragraph (26) on which the housing edge (88) abuts radially circumferentially.

4. Electric motor according to one of the preceding claims, characterized in that the at least one bearing flange (10) has a bearing (30) in a bearing seat (16), and the bearing (30) of a flanged contour (22) on its flanschabgewandten side (32) is peripherally embraced.

5. A method for producing an electric motor (100), wherein a housing (82) with at least one bearing flange (10, 40) is connected, characterized in that a riveting on a bowling alley about a in the housing (82) inserted bearing flange ( 10, 40) rotates and the housing (82) at its housing edge (88, 90) circumferentially on the bearing flange (10, 40) applies.

6. The method according to claim 5, characterized in that the Nietstempel with feed and contact pressure continuously on the housing edge (88, 90) moves.

7. The method according to claim 5 or 6, characterized in that the housing edge (88, 90) so long on the bearing flange (10, 40) is crimped until a positive connection between the housing edge (88, 90) and bearing flange (10, 40) is formed.

8. The method according to any one of claims 5 to 7, characterized in that a bearing (30) in the bearing flange (10) is used and from a lagerflanschabgewandten side (32) of the bearing (30) ago a stamp on a Bowling alley over a contour (20, 22) rolls and a part of the contour (22) radially inwardly umgelegt so that the bearing (30) is overlapped by the contour (22).

9. bearing flange of an electric motor (100) according to at least one of claims 1 to 4, wherein the bearing flange (10, 40) has a rotation axis (64), characterized by a außenumfängliche contour (24, 50) extending from an edge ( 18, 48) of larger circumference tapers in the axial direction, wherein the contour (24, 50) for positive connection with a housing edge (88, 90) is provided.

10. Bearing flange according to claim 9, characterized in that the contour (18, 50) is rounded in the axial direction.

1 1. A bearing flange according to claim 9 or 10, characterized in that concentric with the axis of rotation (64) a shoulder (26) is arranged, which is provided as a stop for the housing edge (88).

12. Bearing flange according to at least one of claims 9 to 11, characterized by a bearing seat (16) with a bearing (30), wherein the bearing (30) on its lagerflanschabgewandten side (32) of material of the bearing flange (10) is overlapped.

13. Power tool, in particular power tool with a striking and / or rotationally driven insert tool (112), with an electric motor (100) according to one of claims 1 to 4 and at least one bearing flange according to one of claims 9 to 12 ..